Some of my best friends are vegan. They gladly come over to my BBQs when I'm grilling a brisket or tri-tip, and I'll always grill extra veggies for them. They don't always talk about being vegan and don't shame me for eating meat. Don't rush to assume the entire group is bad because you've had a few bad experiences with them.
This has the same energy as people who think every queer person is either a butch lesbian or an effeminate gay guy. You can't know unless they tell/show you, so if you don't ask, the only people you'll see are 'obvious' already.